Both large-scale cargo container inspection system and security inspection system utilize radiation imaging to obtain radiographic image of objects by scanning the internal thereof under non-contacting condition with high-energy X-rays having penetration ability. In order to meet the requirements of laws on road traffic safety, safety off-ground space must be kept and special off-ground angle included between a vehicle-carried inspection system and a road when the vehicle is moving on the road, which generally results in a relatively high position of the radiation sources in the scanning device of the inspection system. Consequently, relatively large area in the lower part of the object being inspected can not be detected when performing inspection by radiation scanning. In other words, most existing vehicle-carried radiation inspection systems have a drawback of large scanning blind area.
CN2572400Y discloses a vehicle-carried mobile cargo container inspection system. As shown in FIG. 5, when inspecting a cargo container and its carrying vehicle by the inspection system, rotatable platform 15 mounted on scanning vehicle 1 first horizontally turns 90 degrees. Then, bracket 18, horizontal suspension arm 19 and vertical suspension arm 20 form a portal-shaped frame which straddles the cargo container to be inspected. Finally, radiation sources which will generate X-rays face the orthogonal arms 19 and 20. When performing inspection, radiation sources generate X-rays which penetrate through the cargo container being inspected and its carrying vehicle, and the detectors mounted in arms 19 and 20 then receive the penetrating X-rays. When moving the inspection system, rotatable platform 15 mounted on scanning vehicle 1 turns back 90 degrees, and arms 19 and 20 then overlap each other so as to horizontally lie on scanning vehicle 1. In this inspection system, cabin can be located apart from the ground by a small distance so that fan-shaped X-ray beam 12 generated by radiation sources mounted in cabin may penetrate through the cargo container being inspected and its carrying vehicle at a lower level, thereby enlarging the detection scope, e.g., the chassis of the container carrying vehicle may be detected. However, just due to the small distance from the ground to cabin 6, risk would occur when scanning vehicle 1 is moving.
CN1401995A also discloses a vehicle-carried cargo container inspection system. As shown in FIG. 6, radiation sources device 16 can slide up and down along vertical guide 11 so as to meet the requirements of the detection scope for the object to be inspected. Radiation sources device 16 is lifted to a higher position and locked there to avoid damage during transportation. Although this system may enlarge detection scope, risk would still occur during its transportation because guide 11 per se is located low.